1. Field of the Invention
This invention relates to electronic circuits, and more particularly, to ring oscillator circuits.
2. Description of the Related Art
Many modern integrated circuits employ frequency scaling and/or voltage scaling as a method of balancing performance and power consumption. A combination of these two types of scaling, known as dynamic voltage frequency scaling (DVFS) may provide both voltage and frequency scaling. Using DVFS, voltage and frequency may be increased for workloads requiring higher performance. For workloads that are have a lower performance demand, voltage and frequency may be decreased in order to save power. Voltage and frequency may also be reduced in response to higher operating temperatures in some ICs.
The variations in voltage in utilizing DVFS may affect various components. In many ICs, ring oscillators may be used to generate required clock signals. The frequency of a signal produced by a ring oscillator may be a function of voltage. The frequency of a periodic signal produced by a ring oscillator may increase as voltage increases, while the frequency may decrease as voltage decreases. Accordingly, ring oscillators may be useful in producing clock signals for IC's which utilize DVFS. Individual ring oscillators may have specific characteristics with respect to the frequency of a periodic signal produced relative to a voltage received. For ICs and components thereof that utilize DVFS, ring oscillators may be selected having characteristics that correlate with their respective clock load(s), thereby allowing a linear or nearly linear approximation of operating frequency as a function of voltage over a selected voltage range.